1. Field of the Invention
The present invention relates to a heat insulation chamber which is made of heat insulating material and forms an inner chamber for storing an electronic part, and a thermostatic chamber and a cryostat to which the heat insulation chamber is applied.
2. Description of the Related Art
In recent years, many electronic equipments, which are required to have high performance and reliability, are mounted with a thermostatic chamber which accommodates an device applied in order to obtain a stable operating environment with high reliability, has a loose thermal coupling to the outside, and maintains the operating temperature of the device in a desired range.
Also, in recent years, telecommunication technology has progressed remarkably, and to the main part of communication equipment which configures the communication system, minimizing insertion losses and improving noise figures is severely required.
However, the minimization of insertion losses and the improvement of noise figures can be achieved by applying a superconductive filter and a low noise amplifier (LNA) operating at a cryogenic temperature. Therefore, many communication equipments are provided with cryostats for maintaining in a stable condition of an operating temperature of superconductive filters and low noise amplifiers. Such electronic parts are configured of, for example, HEMT or the like.
FIG. 16 is a diagram showing an exemplary configuration of a conventional cryostat.
In the drawing, a cold head 142 is attached to the bottom of a box-like cabinet 141 which is made of heat insulating material, and an electronic part 143, which operates at a cryogenic temperature, is mounted on the top of the cold head 142. Respective through holes 144-1 and 144-2 are formed among the side walls of the cabinet 141, which faces the input and output terminals of the electronic part 143. Respective ends of coaxial cables 145-1 and 145-2 are connected to these input and output terminals. These coaxial cables 145-1 and 145-2 are led to the outside of the cabinet 141 through the through holes 144-1 and 144-2, which are then sealed with the interior of the cabinet 141 maintained under vacuum. The cold head 142 is connected to a refrigerating machine 147 through a pipe 146.
In the cryostat configured as described above, the cold head 142 maintains the temperature of an inner chamber (hereinafter indicated with reference number xe2x80x9c141Axe2x80x9d allotted), which is sandwiched between the electronic part 143 and the interior walls of the cabinet 141, at a cryogenic temperature that the electronic part 143 operates at, by liquid helium circulating through the pipe 146 as a heating medium between the cold head 142 and the refrigerating machine 147.
The electronic part 143 receives input signals given from a circuit disposed outside of the cabinet 141 through the coaxial cable 145-1, performs a predetermined operation (e.g., filtering as the superconductive filter and amplifying as the low noise amplifier as described above) to the input signals to generate output signals and feeds the output signals to a circuit connected through the coaxial cable 145-2.
In other words, the operating temperature of the electronic part 143 is maintained at a desired cryogenic temperature under the temperature control by the refrigerating machine 147, the pipe 146, and the cold head 142, so that the electronic part 143 exhibits predetermined characteristics and performance under the operating temperature and operates in cooperation with the circuit disposed outside of the cabinet 141 as described above.
In the conventional case described above, the coaxial cables 145-1 and 145-2 are not only conductors but also heat conductors. Therefore, the refrigerating machine 147 unnecessarily consumed a large quantity of electric power to keep the operating temperature of the electronic part 143 from rising by absorbing heat flowing from the outside of the cabinet 141 into the input and output terminals of the electronic part 143 through the coaxial cables 145-1, 145-2.
Technologies for decreasing heat quantity of heat flowing in from the outside as described above include, for example, a technology which uses a conductor with a low thermal conductivity for the inner conductor and outer conductor of the coaxial cables 145-1 and 145-2 and a technology which sets the cross section of the inner conductor and outer conductor to a small value. But, none of such technologies have actually been used because insertion losses of the coaxial cables 145-1 and 145-2 increased to an intolerable level.
And, when the quantity of heat flowing in from the outside through the coaxial cables 145-1 and 145-2 is large, either the operating temperature of the electronic part 143 is not secured, or it is necessary to use a refrigerating machine having higher performance as the refrigerating machine 147.
Moreover, in connecting the coaxial cables 145-1 and 145-2 with the input and output terminals of the electronic part 143, they are generally soldered directly, or, each plug previously fitted to the coaxial cables 145-1 and 145-2 is engaged to each receptacle which is previously soldered to the electronic part 143.
However, the thermal expansion coefficients of the input and output terminals of the electronic part 143 and the receptacles or the coaxial cables 145-1 and 145-2 are generally considerably different.
Therefore, there has been a possibility of a disconnection or an unnecessary increase insertion losses between the coaxial cables 145-1 and 145-2 and the input and output terminals of the electronic part 143 during a large change in the temperature of the inner chamber 141A such as at the moment of activating or stopping.
It is an object of the present invention to provide a heat insulation chamber, a thermostatic chamber, and a cryostat which maintain the operating temperature efficiently and also maintain coupling with a circuit disposed outside in a stable condition.
It is also an object of the present invention to improve the performance and reliability of electronic appliances as well as to reduce their costs and dimentions.
The above-described objects are achieved by a heat insulation chamber, which comprises a cabinet which forms an inner chamber for accommodating an electronic part and is made of heat insulating material; and coupling means which is disposed in the inner chamber or the cabinet, connected to the electronic part, and forms a radio transmission path to an antenna disposed outside of the cabinet.
In this heat insulation chamber, the thermal conductivity of the radio transmission path is generally smaller than that of a conductor, so that heat flowing in and out between the outside and the inner chamber is suppressed more than in the prior art. Moreover, an antenna is not disposed in the inner chamber formed by the cabinet.
Therefore, the electronic part of which the operating temperature is maintained in a stable condition and is downsized, allowing the maintenance of high flexibility in arranging the cabinet""s inner layout.
And, the above-described objects can be achieved by a heat insulation chamber, which comprises a cabinet which forms an inner chamber for accommodating an electronic part and is made of heat insulating material; an antenna which is disposed in the inner chamber or the cabinet; a feeder which leads the feeding point of the antenna to the outside of the cabinet;
and coupling means which is disposed in the inner chamber or the cabinet, connects the feeding point to the electronic part, and forms a radio transmission path to the antenna.
In this heat insulation chamber, the thermal conductivity of the radio transmission path is generally smaller than that of a conductor, so heat flowing in and out between the outside and the inner chamber is suppressed more than in the prior art. Besides, both the antenna and the coupling means are disposed in the inner chamber formed of the cabinet, so the transfer characteristics of the radio transmission path suddenly or extensively changing hardly happens even when the outside environment of the cabinet changed.
Therefore, the operating temperature and the operating environment of the electronic part are maintained in a stable condition.
The above-described objects can also be achieved by a heat insulation chamber, which comprises a cabinet which forms an inner chamber for accommodating an electronic part and is made of heat insulating material; and coupling means which is disposed in the inner chamber or the cabinet, is connected to the electronic part, and forms a coupling path with a device disposed outside of the cabinet by static coupling and/or inductive coupling.
In such heat insulation chamber, the thermal conductivity of the coupling path is generally considerably smaller than that of a conductor, so heat flowing in and out between the outside and the inner chamber is suppressed more than in the prior art. Besides, the device is not disposed in the inner chamber formed by the cabinet.
Therefore, the electronic part of which the operating temperature is maintained in a stable condition and is downsized, allowing the maintenance of high flexibility in arranging the cabinet""s inner layout.
The above-described objects can also be achieved by a heat insulation chamber, which comprises a cabinet which forms an inner chamber for accommodating an electronic part and is made of heat insulating material; a device which is disposed in the inner chamber or the cabinet; a conductor which leads the terminal of the device to the outside of the cabinet; and coupling means which is disposed in the inner chamber or the cabinet, is connected to the electronic part, and forms a coupling path with the device by static coupling and/or inductive coupling.
In this heat insulation chamber, the thermal conductivity of the radio transmission path is generally smaller than that of a conductor, so heat flowing in and out between the outside and the inner chamber is suppressed more than in the prior art. Besides, both the antenna and the coupling means are disposed in the inner chamber formed of the cabinet, so the transfer characteristics of the radio transmission path suddenly or extensively changing hardly happens even when the outside environment of the cabinet changed.
Therefore, the operating temperature and the operating environment of the electronic part are maintained in a stable condition.
Besides, the above-described objects can be achieved by forming a partition between the outside of the cabinet and the inner chamber for accommodating the electronic part and disposing the coupling means together with the electronic part in the inner chamber.
According to such configuration, the coupling means is disposed together with the electronic part in the inner chamber, so the operating temperature of the electronic part is maintained in a stable condition, the mechanical configuration is simplified, and coupling with the electronic part can be made close.
The above-described objects can also be achieved by forming a partition between the outside of the cabinet and the inner chamber for accommodating the electronic part and disposing the coupling means in a region sandwiched between the outer wall of the cabinet and the interior wall of the inner chamber.
According to such configuration, the coupling means is disposed in a region other than the inner chamber but within the outer walls of the cabinet.
Therefore, the radio transmission path or the coupling path is formed between the electronic part and the outside of the cabinet in a stable condition without remarkable or sudden changes in transmission characteristics and transfer characteristics owing to the environment and the medium of the inner chamber where the electronic part is disposed.
Besides, the above-described objects are achieved by forming the inner chamber as an aggregate of a plurality n of cells individually including subdomains which are formed by dividing a region where the electronic part is to be disposed.
According to such configuration, thermal couplings among the cells become loose.
Therefore, temperatures of respective parts of the electronic part are individually varied due to the heat flowing in and out between the outside and the inner chamber, and the changes in characteristics are localized due to the variations in temperatures.
The above-described objects are also achieved by configuring the coupling means as an aggregate of a plurality K of coupling means which are individually connected to a plurality K of terminals of the electronic part and disposed in the inner chamber; and forming the inner chamber as an aggregate of a plurality K of cells in which pairs of the plurality K of terminals and the plurality K of coupling means are respectively disposed, and which are divided by a conductor grounded outside.
According to such configuration, the coupling among the cells is suppressed, and pairs of the coupling means and the terminals of the electronic part individually connected to these coupling means are respectively disposed in these cells.
Therefore, undesirable electric coupling in the inner chamber is suppressed or prevented.
The above-described objects can also be achieved by forming the inner chamber in the shape and size capable of containing a casing of the electronic part.
According to such configuration, the electronic part is accommodated in the inner chamber without having the casing removed.
Therefore, the operating temperature of the electronic part is maintained in a stable condition in the heat protection configuration that is formed in duplex structure by the interior of the casing and the inner chamber.
The above-described objects can also be achieved by the coupling means having a filtering characteristic that has a pass band in an occupied band of signals to be transmitted between the electronic part and the outside through the coupling means.
According to such configuration, the band of the signals transmitted between the terminals of the electronic part and the equipments or circuits disposed outside of the cabinet are limited to the occupied band of the signals.
Therefore, noise given through the equipments or circuits or noise generated by the electronic part is suppressed.
The above-described object can also be achieved by setting a thermal conductivity between the outside of the cabinet and the inner chamber to a value that the temperature at which the electronic part operates is maintained under the distribution of temperatures outside of the cabinet.
According to such configuration, the electronic part operates in a stable condition without having means for raising or lowering the temperatures of the inner chamber as long as the outside temperature of the cabinet shifts within the range of temperature distribution applied when the thermal conductivity is determined.
Besides, the above-described objects can be achieved by a thermostatic chamber which comprises the heat insulation chamber configured as described above; and a heat exchanging means that performs heat exchange with an inner chamber formed in a cabinet under control of a thermoregulator which maintains an operating temperature of the electronic part accommodated into the cabinet configuring the heat insulation chamber.
According to such configuration, when activated, the temperature of the inner chamber is set more quickly to a temperature at which the electronic part operates under the heat exchange as compared with the heat insulation chamber in which the heat exchange is not performed at all, and the temperature thus set is securely maintained even under the environment that the outside temperature of the cabinet largely varies.
The above-described objects can also be achieved by a cryostat that is configured by the heat exchanging means that maintains the temperature of the inner chamber at a cryogenic temperature that the electronic part is to operate under control of the thermoregulator.
By this cryostat, energy required for the heat exchange performed by the heat exchanging means is decreased because quantity of heat flowing from the outside of the cabinet into the inner chamber decreases more than in the prior art.
Other objects and features of the present invention will be apparent from the following detailed description with reference to the accompanying drawings.